JP2019198033A - Noise filter - Google Patents

Abstract

To suppress, in a noise filter for reducing power supply noise, magnetic coupling between a common mode choke coil and a capacitor, thereby preventing degradation in attenuation performance of the noise filter, while allowing size and cost reduction of a countermeasure component and a printed wiring board.SOLUTION: A noise filter comprises: a printed wiring board provided with wiring patterns and grounding patterns; a common mode choke coil, having a pair of winding wires, which is mounted on the printed wiring board; and two capacitors mounted on the printed wiring board. One of the capacitors is connected between the wiring pattern connected to one of the winding wires of the common mode choke coil and the grounding pattern. The other one of the capacitors is connected between the wiring pattern connected to the other one of the winding wires of the common mode choke coil and the grounding pattern. One of the capacitors or the other one of the capacitors is arranged so as to be at least partially sandwiched between the printed wiring board and either one of the winding wires.SELECTED DRAWING: Figure 1

Description

  The present application relates to a noise filter.

As a conventional noise filter, a technique disclosed in Patent Document 1 is known. The noise filter described in Patent Literature 1 is connected between a commercial power supply and a power converter, and reduces noise generated by the power converter that is conducted to the commercial power supply side.
Noise generated by power converters includes normal mode noise that propagates between lines and common mode noise that propagates between lines and ground. The noise filter has noise suppression components for each mode. Yes.

About the noise filter of patent document 1, the top view and front view of the noise filter which extracted only the common mode noise countermeasure component are shown in FIG. 11 and FIG. 12, respectively. 11 and 12, common mode choke coil 3 having a pair of windings 3a and 3b, and line bypass capacitors (line-to-ground capacitors; hereinafter simply referred to as capacitors) 40 and 50 are common mode noise countermeasure components. Each component is mounted on the printed wiring board 1. Here, the ground pattern 20 and the wiring pattern 6 formed on the printed wiring board 1 are shown as examples of general patterns that can be formed when components are arranged as shown in FIGS.
In such a noise filter, components are arranged close to each other on the printed wiring board 1 in order to reduce the area of the printed wiring board 1 to reduce the size and cost. That is, for example, as shown in FIG. 12, the height position of the capacitor 50 on the printed wiring board 1 is set to be substantially the same as the height position of the common mode choke coil 3 on the printed wiring board 1.

JP 2011-60566 A JP-A-3-286511

  However, the noise filter to which the technique disclosed in Patent Document 1 is applied has a problem that the common mode choke coil 3 and the capacitors 40 and 50 are magnetically coupled.

  Here, the leakage flux of the common mode choke coil 3 is generated when a normal mode noise current flows through the common mode choke coil. An explanatory view of the noise filter in a state where the leakage magnetic flux of the common mode choke coil 3 is generated is shown in FIG. As shown in FIG. 13, the leakage fluxes 100a and 100b of the common mode choke coil indicated by broken lines are linked to the loop surfaces between the lead wires of the capacitors 40 and 50 (see, for example, Patent Document 2). As a result, an induced current is generated in the common mode noise path including the capacitors 40 and 50, and the attenuation performance of the noise filter is deteriorated. In particular, as shown in FIG. 12, the height position of the capacitor 50 on the printed wiring board 1 is set to be substantially the same as or higher than the height position of the common mode choke coil 3 on the printed wiring board 1. If it is, there is a problem that it is properly affected by the leakage magnetic flux of the common mode choke coil 3.

  When such a noise filter is connected to a power converter, it is necessary to compensate for the attenuation performance of the degraded noise filter in order to keep the generated noise level of the power converter below the limit specified by the official standards. Occurs. For this purpose, it is essential to add a common mode choke coil or capacitor, and to increase the constant, so it is inevitable to increase the size of the noise filter or increase the cost.

  On the other hand, in order to suppress the magnetic coupling between the common mode choke coil 3 and the capacitors 40 and 50, a method of shielding the common mode choke coil 3 with a magnetic member or the like is conceivable. However, the area of the printed wiring board 1 is increased, and Since an additional member is also required, the noise filter is increased in size and cost, and this method is difficult to employ.

  The present application discloses a technique for solving the above-described problems, and is small and inexpensive that can suppress the magnetic coupling between the common mode choke coil and the capacitor and prevent deterioration of the attenuation performance of the noise filter. An object of the present invention is to provide a simple noise filter.

The noise filter disclosed in this application is
A printed wiring board provided with a wiring pattern and a ground pattern;
A common mode choke coil having a pair of windings and two capacitors mounted on the printed wiring board;
With
One of the two capacitors is connected between a wiring pattern connected to one winding of the common mode choke coil and the ground pattern,
The other of the two capacitors is connected between the wiring pattern connected to the other winding of the common mode choke coil and the ground pattern,
At least a part of the one capacitor or at least a part of the other capacitor is disposed between the printed wiring board and any one of the windings of the common mode choke coil. It is characterized by.

  According to the noise filter disclosed in the present application, by suppressing the magnetic coupling between the common mode choke coil and the capacitor, it is possible to suppress the deterioration of the attenuation performance of the noise filter and to reduce the area of the printed wiring board. Therefore, a small and inexpensive noise filter can be provided.

2 is a configuration diagram of a noise filter according to Embodiment 1. FIG. 3 is a plan view illustrating an example of a noise filter according to Embodiment 1. FIG. It is a side view (A arrow line view) of the noise filter of FIG. It is a front view (B arrow view) of the noise filter of FIG. It is explanatory drawing of the noise filter in the state which the leakage magnetic flux of the common mode choke coil of FIG. 2 has generate | occur | produced. It is a figure which shows an example of the noise terminal voltage waveform which generate | occur | produces in the commercial power supply side at the time of connecting a power converter device to the noise filter by Embodiment 1, and the conventional noise filter. FIG. 6 is a front view showing another example of the noise filter according to the first embodiment. 6 is a front view illustrating an example of a noise filter according to Embodiment 2. FIG. It is a figure which shows the structural example at the time of connecting the noise filter by Embodiment 3 in multistage. It is explanatory drawing of the noise filter in the state in which the leakage magnetic flux has generate | occur | produced in the some common mode choke coil which concerns on FIG. It is a top view of the noise filter which extracted only the common mode noise countermeasure component of the noise filter of patent documents 1. It is a front view of the noise filter which extracted only the common mode noise countermeasure component of the noise filter of patent documents 1. It is explanatory drawing of the noise filter in the state which the leakage magnetic flux of the common mode choke coil of FIG. 11 has generate | occur | produced. It is explanatory drawing of a noise filter in the state in which the leakage flux of the common mode choke coil has generate | occur | produced when the conventional noise filter is connected in multistage.

Embodiment 1 FIG.
Hereinafter, the noise filter according to Embodiment 1 of the present application will be described. FIG. 1 is a diagram illustrating an example of a configuration of a noise filter according to Embodiment 1 of the present application. FIG. 2 is a plan view showing an example of the noise filter according to the first embodiment.

  As shown in FIGS. 1 and 2, the noise filter according to the first embodiment includes a common mode choke coil 3 having a pair of windings 3a and 3b and a capacitor (a capacitor between line and ground. Hereinafter, simply referred to as a capacitor). 4 is a noise filter having a single-stage LC (inductance and electrostatic capacity) composed of 4 and 5. Here, as the capacitors 4 and 5, a lead type multilayer ceramic capacitor or a lead type film capacitor is used. Moreover, the side view (A arrow view of FIG. 2) and the front view (B arrow view of FIG. 2) of the noise filter according to Embodiment 1 are shown in FIGS. 3 and 4, respectively.

  2 to 4, the common mode choke coil 3 and the capacitor 4 or the capacitor 5 are mounted on the printed wiring board 1, and the capacitor 4 or the lead terminal of the capacitor 5 is mounted on the printed wiring board 1. A ground pattern 2 for grounding and a wiring pattern 6 for connecting the components are formed.

  2 to 4, the common mode choke coil 3 and the capacitors 4 and 5 are mounted on the printed wiring board 1, and the lead terminals of the capacitors 4 and 5 are grounded on the printed wiring board 1. A ground pattern 2 for connecting the wiring pattern 6 and a wiring pattern 6 for connecting the components to each other are formed. Further, the capacitor 4 is disposed (at least) between the printed wiring board 1 and the winding 3a of the common mode choke coil 3, and the capacitor 5 is arranged between the printed wiring board 1 and the common mode choke coil. 3 (at least) between the three windings 3b.

  As described above, the area of the printed wiring board 1 can be reduced as compared with the printed wiring board disclosed in Patent Document 1. In addition, the ground pattern 2 is provided for each of the capacitors 4 and 5. However, by forming the ground pattern 2 in this way, it is easy to route the pattern of the printed wiring board 1 and the occupied area of the pattern is reduced. The area of the printed wiring board 1 can be further reduced as compared with the case where the ground pattern 2 is a common ground pattern.

  Hereinafter, the principle of suppressing the deterioration of the attenuation performance of the noise filter according to Embodiment 1 configured as described above will be described with reference to the drawings. FIG. 5 is an explanatory diagram of the noise filter in a state where the leakage magnetic flux of the common mode choke coil 3 is generated.

  As shown in FIG. 3, the capacitor 4 is disposed so that a part thereof is sandwiched between the printed wiring board 1 and the winding 3 a of the common mode choke coil 3, and the capacitor 5 is connected to the printed wiring board 1 in common. Since a portion of the mode choke coil 3 is interposed between the windings 3b of the mode choke coil 3, the leakage magnetic fluxes 100a and 100b of the common mode choke coil 3 indicated by broken lines are as shown in FIG. The loop surface generated between the capacitor 4 and the printed wiring board 1 and the loop surface generated between the capacitor 5 and the printed wiring board 1 are not linked to each other.

  As a result, the common mode choke coil 3 and the capacitors 4 and 5 do not cause magnetic coupling, and no induced current is generated in the common mode noise path including the capacitors 4 and 5. It becomes possible.

  Next, the noise attenuation performance of the noise filter described above will be described. FIG. 6 shows a case where both ends of a LISN noise measurement resistor are connected when a LISN (Line Impedance Stabilization Network) defined by CISPR16-1-2 is connected between a commercial power supply and a noise filter to which a power converter is connected. Shows the observed noise terminal voltage. Here, it is assumed that the switching noise of 100 kHz generated by the power converter and the normal mode noise of 10 MHz are propagated from the power converter to the commercial power source.

  In FIG. 6, a solid line P is a noise terminal voltage waveform when the noise filter according to the first embodiment is connected, a one-dot chain line Q is a locus (envelope) of a peak value of the solid line P, and a dotted line R is a conventional line. In the locus (envelope) of the peak value of the noise terminal voltage waveform when the noise filter is connected, the broken line S is the noise limit value of IEC61581-21 defined by the international standard IEC (International Electrotechnical Commission).

  As shown in FIG. 6, since switching noise of 100 kHz propagates from the power converter, the noise spectrum has harmonics generated at 100 kHz intervals with 100 kHz as the fundamental wave. Further, since normal mode noise of 10 MHz is propagated from the power converter, resonance noise is generated at 10 MHz.

  Here, when focusing on the resonance noise of 10 MHz, it can be confirmed that the dashed line Q has a lower noise level than the dotted line R. This is because the noise filter according to Embodiment 1 has better attenuation performance than the conventional noise filter.

  In the case of a conventional noise filter, when a normal mode noise current of 10 MHz propagates, the common mode choke coil and the capacitor are magnetically coupled, and a 10 MHz common mode current flows through the common mode path including the capacitors 4 and 5, and the commercial power supply side Propagate to.

  On the other hand, in the noise filter according to the first embodiment, since the magnetic coupling between the common mode choke coil and the capacitor is suppressed, a 10 MHz common mode current does not flow through the common mode path including the capacitors 4 and 5.

  Further, in the first embodiment, in the thickness direction of the printed wiring board 1, the capacitors 4 and 5 are respectively sandwiched between the printed wiring board 1 and the winding 3a or the winding 3b of the common mode choke coil. However, the present invention is not limited to this, but, for example, as shown in FIG. 7, only one of the capacitors 4 and 5 is common to the printed wiring board 1. The same effect can be obtained also when a part (at least) of the mode choke coil is interposed between the windings of the mode choke coil.

  In the above description, the capacitors 4 and 5 are not limited to the case where each capacitor is composed of one capacitor as shown in the configuration of the noise filter described above, and a plurality of capacitors are connected in parallel. Also good. In general, a capacitor has a larger component volume in proportion to the capacity. Since a capacitor having a relatively small capacity is connected in parallel, the capacitor can be arranged within the winding width of the common mode choke coil 3 in which the leakage flux of the common mode choke coil 3 is smaller. Further, it is possible to configure a noise filter in which the magnetic coupling between the common mode choke coil 3 and the capacitors 4 and 5 is suppressed.

Embodiment 2. FIG.
Next, the noise filter according to Embodiment 2 will be described below with reference to FIG.
In the noise filter of the second embodiment, capacitors 4 a and 5 a are sandwiched between the printed wiring board 1 and the windings 3 a and 3 b of the common mode choke coil 3 in the thickness direction of the printed wiring board 1. However, the size in the width direction (left and right direction in the drawing) is smaller than that of the capacitors 4 and 5 of the first embodiment, and the printed wiring board is the same as the capacitor 4 and 5 of the noise filter of the first embodiment. 1 and the windings 3a and 3b of the common mode choke coil 3 are different from the noise filter according to the first embodiment in that they are arranged in a form (not part of them) between them. In other words, the lateral width (size) of the capacitors 4a and 5a is defined by the lateral size occupied by the windings 3a and 3b of the common mode choke coil 3 (or the donut shape of the common mode choke coil 3 is defined). It differs from the noise filter of the first embodiment in that it is arranged (defined by two concentric contours on the inside and outside).

  In the noise filter of the second embodiment, as in the case of the noise filter of the first embodiment, the capacitors 4a and 5a are not limited to the case where each capacitor is constituted by one capacitor shown in FIG. A plurality of capacitors may be connected in parallel.

  According to the noise filter of the second embodiment, the capacitor can be disposed within the winding width of the common mode choke coil 3 in which the leakage flux of the common mode choke coil 3 is smaller. A noise filter in which the magnetic coupling between the mode choke coil 3 and the capacitors 4 and 5 is suppressed can be configured.

Embodiment 3 FIG.
Next, the noise filter according to Embodiment 3 will be described below with reference to the drawings.
In the above-described first embodiment, either the combination of the common mode choke coil 3 having the pair of windings 3a and 3b and the capacitors 4 and 5, or the common mode choke coil 3 and the capacitors 4 and 5 is selected. Although the LC composed of one combination has been described with a one-stage configuration, in the third embodiment, the LC has a two-stage configuration, for example, a common mode choke coil 3 having a pair of windings 3a and 3b, and This is a case where the combination of both capacitors 4 and 5 is one stage and this combination is two stages. The noise filter according to the third embodiment will be described below with reference to FIGS. According to the noise filter having the configuration shown in these drawings, the effect of suppressing the attenuation performance of the noise filter can be further obtained.

  FIG. 9 is a diagram illustrating a configuration in which the noise filter according to the third embodiment is connected in multiple stages to form an LC two-stage configuration. FIG. 10 is an explanatory diagram of the noise filter in a state where leakage magnetic flux is generated in the common mode choke coil 3 of the noise filter according to the third embodiment configured as shown in FIG.

  As shown in FIG. 10, in the present embodiment, the windings 3a, 13a and 3b, 13b of the two common mode choke coils 3, 13 share the wiring patterns 6 shown in the upper and lower rows, respectively. It is mounted with. That is, of the two common mode choke coils 3 and 13, one common mode choke coil, for example, a wiring pattern connected to one winding 3 a of the common mode choke coil 3 and the other common mode choke coil 3. The other common mode choke coil 13 is connected in series to the wiring pattern connected to the winding 3b.

  In the present embodiment, the capacitor 4 is arranged in a space partially sandwiched between the printed wiring board 1 and the winding 3a of the common mode choke coil 3, and the capacitor 5 is connected to the printed wiring board 1 and the common mode choke. Arranged in a space partly sandwiched between the windings 3b of the coil 3 and the capacitor 14 disposed in a space partly sandwiched between the printed wiring board 1 and the windings 13a of the common mode choke coil 13. Since the capacitor 15 is disposed in a space partially sandwiched between the printed wiring board 1 and the winding 13b of the common mode choke coil 13, the capacitor 15 is indicated by a broken line as shown in FIG. The leakage fluxes 100a and 100b of the common mode choke coil 3 are caused by the loop surface generated between the capacitor 4 and the printed wiring board 1, the capacitor 5 and the plug, respectively. In addition, the leakage fluxes 200a and 200b of the common mode choke coil 13 are not linked to the loop surface generated between the capacitor 14 and the printed wiring board 1, respectively. 15 is not linked to the loop surface formed between the printed circuit board 1 and the printed wiring board 1.

  Accordingly, the common mode choke coil 3 and the capacitors 4 and 5 do not cause magnetic coupling, the common mode choke coil 13 and the capacitors 14 and 15 do not cause magnetic coupling, and the common mode noise path including the capacitors 4 and 5 and the capacitor Since no induced current is generated in the common mode noise path including 14 and 15, it is possible to suppress the attenuation performance deterioration of the noise filter.

  As in the case of the first embodiment having the LC one-stage configuration, in the case of the third embodiment having the LC two-stage structure, the magnetic coupling between the common mode choke coil 3 and the capacitors 4 and 5, and the common mode choke coil 13 The magnetic coupling of the capacitors 14 and 15 is suppressed.

  On the other hand, FIG. 14 shows an explanatory diagram of the noise filter in a state where leakage magnetic flux is generated in a plurality of common mode choke coils when the conventional noise filter has an LC two-stage configuration. As shown in FIG. 14, in the capacitors 40 and 50, in addition to the leakage fluxes 100a and 100b of the common mode choke coil 3, the leakage fluxes 200a and 200b of the common mode choke coil 13 are also magnetically coupled. Compared with the case, the deterioration of the attenuation performance of the conventional noise filter becomes more remarkable.

In the present application, exemplary embodiments are described. However, various features, aspects, and functions described in the embodiments are not limited to application of specific embodiments, and are independent. The present invention can be applied to the embodiments in various combinations.
Accordingly, countless variations that are not illustrated are envisaged within the scope of the technology disclosed herein. For example, the case where at least one component is modified, the case where it is added, or the case where it is omitted are included. Specifically, for example, in the third embodiment, the capacitors may be arranged in two sets as shown in FIG. 7, and each of the capacitors shown in FIGS. You may make it have one each, and you may make it have one set of FIG. 2 and FIG. In either case, the attenuation performance of the noise filter is improved as compared with the conventional noise filter.

  1 Printed wiring board, 2 Ground pattern, 3, 13 Common mode choke coil, 3a, 3b, 13a, 13b Winding, 4, 4a, 5, 5a, 14, 15 Capacitor, 6 Wiring pattern, 100a, 100b, 200a, 200b Magnetic flux leakage

The noise filter disclosed in this application is
A printed wiring board provided with a wiring pattern and a ground pattern;
It mounted on the printed circuit board, and the common mode choke coil and two capacitors having a pair of windings,
With
One of the two capacitors is connected between a wiring pattern connected to one winding of the common mode choke coil and the ground pattern,
The other of the two capacitors is connected between the wiring pattern connected to the other winding of the common mode choke coil and the ground pattern,
At least a part of the one capacitor or at least a part of the other capacitor is disposed between the printed wiring board and any one of the windings of the common mode choke coil. The leakage flux of the common mode choke coil is a loop surface generated between the one capacitor and the printed wiring board, and a loop surface generated between the other capacitor and the printed wiring board. The structure is such that at least one of the loop surfaces does not interlink .

Claims (4)

A printed wiring board provided with a wiring pattern and a ground pattern;
A common mode choke coil having a pair of windings and two capacitors mounted on the printed wiring board;
With
One of the two capacitors is connected between a wiring pattern connected to one winding of the common mode choke coil and the ground pattern,
The other of the two capacitors is connected between the wiring pattern connected to the other winding of the common mode choke coil and the ground pattern,
At least a part of the one capacitor or at least a part of the other capacitor is disposed between the printed wiring board and any one of the windings of the common mode choke coil. Noise filter characterized by. At least a part of the one capacitor is disposed between the printed wiring board and one winding of the common mode choke coil, and
2. The noise filter according to claim 1, wherein at least a part of the other capacitor is disposed between the printed wiring board and the other winding of the common mode choke coil. Having two common mode choke coils,
A wiring pattern connected to one winding of one of the common mode choke coils, and a wiring pattern connected to the other winding of the one common mode choke coil,
The noise filter according to claim 1 or 2, wherein the other common mode choke coil of the two common mode choke coils is connected in series. 4. The noise filter according to claim 1, wherein the ground pattern is provided on each of the one capacitor and the other capacitor. 5.

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